Wireless data devices are known in principle and are used in medical monitoring for high-risk patients or remote maintenance and diagnosis of technical equipment. Such equipment may, communicate technical or medical data to a data acquisition and evaluation center by way of a cellular radio or wireless data network, and may possibly receive instructions from the same.
In that respect, portable devices are often utilized for the home monitoring of high-risk patients, such devices having a second telemetry interface for communication with an electromedical implant. Modern electromedical implants, in particular cardiac pacemakers, defibrillators and the like afford physician and patients a very high degree of security and comfort by virtue of those home-monitoring functions.
In that respect the implant processes diagnosis and therapy information and transmits items of information to an external patient device by way of a telemetry interface. From there the data are passed to what is referred to as a home monitoring service center (HMSC) where they are stored and displayed for the physician. In that way the physician can be informed directly about therapy progress and the current state of health of his patients and enjoys the possibility of reacting quickly to possible changes in health.
Without home monitoring the physician can obtain those items of information only in the context of an examination of the patient. In critical situations, that would result in unwanted delays in the flow of information. In addition any examination involves a considerable amount of time, both for the physician and the patient. Frequent examination has an adverse effect on the mobility and quality of life of the patient.
In home monitoring, the implant information is sent via the patient device (see U.S. Pat. Nos. 6,553,262 and 5,752,976) in the background without the patient being limited in terms of leading a normal life. In other words, the patient enjoys the security of physician monitoring without the stress of frequent examinations.
In the case of the technical device, continuous monitoring means that it is possible to recognize particular operating conditions so that further operation of the device can be guaranteed.
As the freedom of movement of a patient is not to be unnecessarily restricted, data transmission is preferably effected by way of one of the extensively available cellular radio networks, in particular the GSM, UMTS or a CDMA network. Data transmission by way of a WLAN network can also be envisaged. The advantage of ease of connection by way of one of those wireless communication networks is rather in the foreground, but it is also possible to imagine movable items of equipment in respect of which the aspect of unrestricted mobility is also to be considered. Thus a similar device could be used in vehicles involved in goods delivery or personal transport in order, for example, to communicate to a control center various data including location, loading and technical data such as the tank filling level or the temperature of the load space. In that case the vehicle and the device are usually combined to form one unit.
The development of a device of the described kind together with the cellular radio interface may be very complicated and expensive. In practice, therefore it may be made up in part from prefabricated modules, which afford given functions. That applies in particular to the cellular radio interface, which is normally embodied by a cellular telephone incorporated into the device or a prefabricated cellular radio module with full functional extent.
In order to authenticate the access authorization to a wireless communication network devices equipped with a cellular radio interface are provided with a user identity module which uniquely identifies the device or its operator on the basis of items of information stored on the user identity module. When logging on to a wireless communication network the device communicates those items of information to that network which then checks the access authorization of the device by a comparison with a centrally stored copy. Identification is inter alia therefore a necessary prerequisite for use of a mobile service as it is only thereby that the connection costs incurred can be billed. Therefore it is also always involved in so-called ‘roaming’, that is to say the use of network resources and services of cellular radio network operators in other region or countries. In the case of a device which is designed to communicate by way of a GSM network the user identity module is in the form of what is referred to as a SIM card, the copy of the access authorization is stored in what is referred to as the ‘home location register’ (HLR).
If an access authorization to the wireless communication network in question cannot be established, the wireless communication network communicates to the device, which is seeking to log on a request to refrain from further log-on attempts in relation to the same network in order to husband the resources thereof. As a standard procedure, cellular telephones and cellular radio modules take account of that information about a rejection and refrain from further log-on attempts in relation to the communication network in question. A further log-on attempt can be triggered only by operating the keypad of the cellular telephone or the cellular radio module. If there is no keypad or if it is inaccessible a further log-on procedure cannot be initiated at all.
A log-on attempt in relation to a communication network is also rejected thereby when checking of the access authorization is not possible. That occurs, for example, when a connection could not be made to the HLR, due to a fault. Such accesses can be the subject of interference particularly when roaming because of the more complicated access to the HLR.
Under some circumstances, a device may be rejected by all receivable networks and of its own accord ceases all further attempts to form a connection by way of a wireless communication network. It can then only be moved to make further log-on attempts by virtue of external intervention. As however either the user of the device is not to be bothered due to a complicated user interface or however there is no one at all present on the spot, operation of a device of the described kind in accordance with the state of the art can no longer be guaranteed.
Therefore, it would be advantageous to provide a device and a method of operating such a device, which even after rejection by all receivable wireless communication networks, permits a communication of the device with the home monitoring service center if the cause of the rejection is no longer there.